Designed as an economical, flexible pan liner for use in tile shower and other concealed water-proofing applications. Liner is marked ever 6" to allow for easy measuring of material. An effective water-barrier in tile shower or other concealed water-proofing applications. IAPMO Listed. Meets ASTM D4551. Without Dam corners. 40 mil. Gray. Any other size also available, if you have any questions please call me at (727) 776-78-62